Automatic wheel bearing lubricator

Abstract

An automatic lubricator for wheel bearings and closure cap for wheel hubs comprises a hollow body having an open end connected with the hub, a piston sealingly and slidably mounted in the body, and a spring member urging the piston toward the bearing and constantly applying a positive pressure on the lubricant packing the hub. A lubrication fitting for filling the lubricator is attached to the body adjacent to the open end thereof, and an overflow aperture is disposed through a side wall of the body at a point adjacent to the piston for relieving excess lubricant pressure. A heat responsive member located in the body is operative to release lubricant from the hub cavity in response to an abnormally high lubricant temperature.

I claim: 
     
       1. A wheel bearing lubricator comprising: a. a hollow body having side walls, a central aperture, a first end, a medial portion, and a second end; said first end being adapted for sealing engagement with a wheel hub; said second end having a substantially cylindrically shaped interior surface, and said medial portion having an relatively enlarged interior surface;   b. a piston slidably mounted within said second end; said piston having a marginal edge thereof normally sealingly engaging the interior surface of said second end; said piston being slidably mounted in said body for translation into said medial portion wherein the marginal edge of said piston assumes a non-sealing position with respect to the interior surface of said medial portion;   c. a relief opening positioned through said body and disposed rearwardly of said piston and in spaced relation thereto;   d. resilient means urging said piston toward said medial portion; and   e. means normally limiting piston travel to translation within the second end of said body; said limiting means being heat responsive whereby upon attaining a predetermined temperature, said limiting means releases said piston, and said resilient means urges said piston into the medial portion of said body and into said non-sealing position therewith thereby allowing lubricant to flow from said medial portion and through said relief opening, and escape from the lubricator as a warning signal.   
     
     
       2. A wheel bearing lubricator as set forth in claim 1 wherein said limiting means comprises: a. a retainer connected with said second end and projecting inwardly from the interior surface thereof;   b. a disc having a circular shape and a peripheral portion; said disc being positioned between said retainer and said piston; the peripheral portion of said disc abuttingly engaging said retainer whereby the travel of said piston is limited to a normally forwardmost position wherein said resilient means is tensioned and urges said piston toward said medial portion; and   c. said disc being constructed of a heat responsive material whereby upon attaining a predetermined temperature, the shape of said disc distorts and the peripheral portion thereof disengages said retainer.   
     
     
       3. A wheel bearing lubricator as set forth in claim 1 wherein said limiting means comprises: a. a retainer connected with and projecting inwardly of the interior surface of said second end; said retainer having a cross sectional, protruding shape;   b. a disc having a circular shape and a peripheral portion; said disc being positioned between said retainer and said piston; the peripheral portion of said disc abuttingly engaging said retainer whereby the travel of said piston is limited to a normally forwardmost position wherein said resilient means is tensioned and urges said piston toward said medial portion; and   c. said retainer being constructed of a heat responsive material whereby upon attaining a predetermined temperature, the shape of said retainer distorts and disengages the peripheral portion of said retainer.   
     
     
       4. Wheel bearing lubricator as set forth in claim 1 including: an overflow aperture disposed through the side walls of said body at a point thereon disposed adjacent to said piston whereby the pressure of lubricant in said hub moves said piston away from said first end to a position wherein said hub and said overflow aperture are communicating to prevent excess grease pressure.   
     
     
       5. A wheel bearing lubricator comprising: a. a hollow cap having upstanding side walls, a central aperture, an open end, a medial portion, and a closed end; said open end being adapted for sealing engagement with a wheel hub; said closed end and said medial portion each having an interior surface with a substantially cylindrical shape and a diameter; the diameter of said medial portion being larger than the diameter of said closed end, and forming a stepped shoulder between said medial portion and said closed end;   b. a tubular member having connection with a central portion of said closed end and extending therefrom between and concentrically with said side walls;   c. a lubrication fitting connected with said closed end and communicating with said tubular member;   d. a piston slidably and sealingly mounted on said tubular member and having a marginal edge thereof normally sealingly engaging the interior surface of the closed end; said piston being slidably mounted on said tubular member for translation into said medial portion wherein the marginal edge of said piston assumes a non-sealing position with respect to the interior surface of said medial portion;   e. a spring member positioned between said piston and said closed end, and urging said piston toward said medial portion;   f. a vent aperture disposed through said cap at a point adjacent to said closed end; and   g. means normally limiting piston travel to translation within the closed end of said body; said limiting means being heat responsive whereby upon attaining a predetermined temperature, said limiting means releases said piston, and said resilient means urges said piston past said stepped shoulder into the medial portion of said body and into said non-sealing position thereby allowing lubricant to flow from said medial portion through said vent aperture, and escape from the lubricator as a warning signal.   
     
     
       6. A wheel bearing lubricator as set forth in claim 5 wherein said limiting means comprises: a. a lip connected with, projecting inwardly from, and extending circularly around the interior surface of said side walls in said closed end at a point disposed adjacent to said medial portion;   b. a disc having a circular shape and a peripheral portion; said disc being positioned between said lip and said piston; the peripheral portion of said disc abuttingly engaging said lip whereby the travel of said piston is limited to a normally forwardmost position wherein said resilient means is compressed and urges said piston toward said medial portion; said disc having first and second apertures therethrough; said first aperture being disposed through a central portion of said disc and communicating with said tubular member, and said second aperture being disposed between the central and peripheral portions of said disc for communicating hub lubricant pressure to said piston; and   c. said disc being constructed of a heat responsive material whereby upon attaining a predetermined temperature, the shape of said disc distorts and the peripheral portion thereof disengages said lip.   
     
     
       7. A wheel bearing lubricator as set forth in claim 6 including: a. an overflow aperture disposed through said side walls at a point thereon disposed adjacent to said closed end whereby the pressure of lubricant in said hub moves said piston away from said open end to a position wherein said central aperture and said overflow aperture are communicating to prevent excess grease pressure.   
     
     
       8. A wheel bearing lubricator as set forth in claim 7 including: a. a backing disc having a central aperture therethrough, and being slidably connected with said tubular member and positioned between said piston and said spring member.   
     
     
       9. A wheel bearing lubricator as set forth in claim 7 wherein: a. said closed end includes a central, recessed portion, and said lubrication fitting is disposed therein, whereby a top surface of said fitting and said closed end are respectively substantially coplanar.   
     
     
       10. A wheel bearing lubricator as set forth in claim 7 wherein: a. said spring member comprises a helically coiled wire spring; and   b. said cap member is constructed of a transparent synthetic resin material.